An ambient-cured coating film obtained via a Knoevenagel and Michael addition reactions based on modified acetoacetylated castor oil prepared by a thiol-ene coupling reaction

Abstract

A novel ambient-cured coating film obtained via a Knoevenagel and Michael addition reactions between modified acetoacetylated castor oil and a crosslinker that contain both aldehyde and acrylate groups was developed. The modified acetoacetylated castor oil was synthesized via thiol-ene coupling and transesterification reactions and was characterized by NMR, FTIR, and viscosity analyses. The coating films prepared by the Knoevenagel addition reaction, Michael addition reaction, and Knoevenagel and Michael addition reactions coating film are discussed. The tensile and thermal properties of the obtained coating films were investigated by dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results demonstrated that the Knoevenagel and Michael addition reactions coating film has a good balance of properties. Moreover, we also prepared films with different crosslinkers by Knoevenagel and Michael addition reactions and found that the films have good properties, including glass transition temperature (41%–54%), pencil hardness (3 H), and tensile properties (1.17 MPa – 2.23 MPa). Overall, the film made via Knoevenagel-Michael addition technology provides an excellent bio-based coating system.